The testis is the center for spermatogenesis, the process by which a germ cell proceeds through multiple stages of differentiation, and culminates in the formation of a terminally differentiated cell (spermatozoa or sperm) having a unique function. Within the testis are seminiferous tubules, where spermatogonium mature into spermatozoa. Surrounding the seminiferous tubules are interstitial cells which secrete androgens, such as testosterone, required for maturation and function of the testis and development of secondary sexual characteristics. Disorders of the testis are common and have profound effect. Infertility can result from disorders occurring during spermatogenesis. Many developmental disorders, such as hypogonadism, are associated with altered sex hormone production and levels in the testis. Testicular cancer, although rare, is the most common form of cancer in young men between the ages of 15 and 35.
Testis specific proteins have therapeutic value in the treatment of disorders associated with the testis such as dysfunctional sperm production, infertility and testicular cancer. Towards this end, the present invention provides novel testis-specific membrane glycoproteins, soluble ligands, agonists and antagonists, related compositions and methods as well as other uses that should be apparent to those skilled in the art from the teachings herein.